1. Field of the Invention
The present invention relates to an ink tank and a recording apparatus which can detect the amount of ink remaining.
2. Related Background Art
For example, the recording apparatus in which an image is recorded with liquid ink can be cited as an example of the recording apparatus using liquid. An ink jet recording apparatus, in which the image is recorded on a recording medium by using an ink jet recording head which can discharge the liquid ink to provide the ink onto the recording medium, can be cited as an example of the recording apparatus in which an image is recorded with liquid ink. In the ink jet recording apparatus, noise is relatively small during the recording and small dots can be formed in high density, so that the ink jet recording apparatus is currently utilized in many recording applications including color recording. In one of forms of the ink jet recording apparatus, there is the type of ink jet recording apparatus using the ink jet recording head to which an ink tank is integrally or separably attached. The ink jet recording apparatus using the ink jet recording head to which the ink tank is integrally or separably attached includes a carriage on which the ink jet recording head is mounted and which causes the ink jet recording head to relatively scan in a predetermined direction relative to the recording medium (main scan) and conveying means for conveying relatively the recording medium in the direction (sub-scan) orthogonal to the direction in which the ink jet recording head is scanned. In the main scan of the ink jet recording head, the ink is discharged from the ink jet recording head to perform the recording. The ink jet recording apparatus also includes one in which not only monochrome recording for a text image can be performed only with black ink, but also full color recording can be performed by mounting the recording head in which both the black ink and color ink (yellow, cyan, magenta, and the like) can be discharged to change a rate of discharge of each color ink.
In the use of the ink jet recording apparatus, it is necessary to grasp the amount of ink remaining in the ink tank.
In the ink jet recording apparatus, detection of the amount of ink remaining can prevent recording failure caused by the absence of the ink and waste of the recording paper incident to the recording failure. When the ink jet recording head including means for generating thermal energy such as an electrothermal transducer is used as means for discharging the ink, the ink is discharged by utilizing pressure generated by a change in state of the ink to which the thermal energy is given. In the ink jet recording apparatus adopting the electrothermal method, the detection of the amount of ink remaining can encourage a user to change the ink tank in order to prevent breakage of the ink jet recording head of itself caused by temperature rise of the ink jet recording head when the thermal energy generating means is driven while the ink is absent. For example, the amount of ink remaining can be displayed by detecting the amount of ink remaining in the ink tank, an alarm can be issued in the case of the small amount of ink remaining, and the recording operation can be stopped with these notifications.
Conventionally, the configuration which uses an optical element to detect a permeable state of the ink tank changed according to the amount of ink remaining, and the configuration which detects an electrically conductive state changed according to a liquid level of the ink by using a plurality of electrode members arranged inside the ink tank (hereinafter these are referred to as sensor type) can be cited as an example of the configuration for detecting that the ink is used up in the ink tank (ink end). The configuration, in which the number of discharge pulses for discharging the ink from the ink jet recording head is counted to determine the amount of used ink and the amount of ink remaining is estimated based on the amount of used ink (hereinafter referred to as dot count type), is well known as another method of detecting the amount of ink remaining.
The ink volume detecting method disclosed in Japanese Patent Application Laid-Open (JP-A) No. H07-125251 can be cited as still another example. In the method of JP-A No. H07-125251, an ink liquid chamber including a diaphragm and a core which shift according to the amount of ink remaining is provided in an ink channel which supplies the ink in the ink tank to the ink jet recording head, and the amount of ink remaining is detected by changing a position of the core in a coil outside the ink channel.
In the ink volume detecting method disclosed in JP-A No. H10-217508, the coil is wound around the outside of the ink channel which supplies the ink from the ink tank to the ink jet recording head or at least a part of the ink tank, and the amount of ink remaining is detected from inductance of the coil changed by the amount of ink inside the coil.
In the sensor type using the optical element or the electrode member, it is necessary to add the number of components in order to detect the amount of ink remaining in stages, which causes a problem that production cost is increased. Further, it is necessary to secure a space for arranging the component such as the optical element, so that it is difficult to detect the amount of ink remaining in multi stages, and usually the liquid level of the ink is detected only in the ink end.
In the dot count type counting the number of discharge pulses of the ink, because the amount of ink remaining is estimated while variations in the amount of ink used in forming the dot are included, when the amount of ink remaining is detected at any point from the state in which the ink tank is filled with the ink to the state in which the ink is used up, there is the problem that error of the amount of ink remaining is absolutely caused to hardly detect the correct ink end point.
In the case of the type of JP-A No. H07-125251, since the ink liquid chamber is enlarged, there is the problem that the ink liquid chamber can not be integrated with the carriage which is formed so that the small ink tank is detachably mounted. Particularly, when the plurality of ink tanks is provided for the color recording, since the ink liquid chamber is provided corresponding to each color ink tank, there is the problem that the ink jet recording apparatus is upsized and the cost is increased.
For the method of winding the coil around the ink channel in the case of the type of JP-A No. H10-217508, since the amount of ink remaining can not be detected in stages, the liquid level of the ink is detected only in the ink end. In the method of winding the coil around the ink tank, the amount of ink remaining can be linearly detected to a certain extent. However, since the ink is arranged only inside the coil, in the ink except for magnetic ink disclosed in JP-A H10-217508, there is the problem that magnetic fluxes are largely decreased near the coil and the change in inductance is decreased to worsen the detection accuracy.
As described above, in the sensor type, there is the problem that the number of components is increased and the space is difficult to secure in order to detect the amount of ink remaining in stages. In the dot count type, there is the problem that the error is generated in the amount of ink remaining. In the method of winding the coil around the ink tank as described in JP-A No. 10-217508, when the ink except for the magnetic ink is used, there is the problem that the change in inductance of the coil changed by the ink volume inside the ink tank is decreased.